ELECTRON-MICROSCOPY STUDIES OF THE MERCURY-BASED SUPERCONDUCTOR HGBA2CUO4+DELTA

The new Hg-based superconductor HgBa2CuO4+delta has been studied with scanning electron microscopy, high-resolution electron microscopy and energy dispersive spectrometry analysis. The diffraction patterns confirmed the primitive unit cell obtained from X-ray powder data (space group P4/mmm, a = 3.8797 (5) angstrom, c= 9.509 (2) angstrom) and showed that the structure is well ordered. The metal content is approximately the same as in the above formula, recently proved by X-ray analysis [Putilin et al., Nature 362 (1993) 226]. It was possible to obtain high-resolution photographs in reasonable agreement with simulated images. Besides the superconducting phase, some other phases exist in the synthesized samples, one of them probably amorphous. The possibility of intergrowths between different members of the homologous series HgBa2Rn-1CunO2n+2+delta is shown.